In Paris, a carnival brings excitement as Dr. Mirakle, a sinister and charismatic scientist, showcases his gorilla named Erik to the public. Mirakle's true intentions are far darker; he is conducting experiments to prove that apes and humans can interbreed. Among the spectators are Pierre Dupin, an intelligent medical student, and his spirited girlfriend, Camille. Mirakle sets his eyes on Camille, seeing in her the perfect subject for his grotesque aspirations. When women from the poorer quarters of the city start disappearing, only to be found dead with strange puncture marks on their necks, Dupin begins to investigate, suspecting a connection between the killings and Mirakle's macabre displays.

As tensions rise, Dupin's investigation leads him deeper into the twisted plans of Mirakle, where he discovers that the mad scientist's methods are even more horrific than he imagined. The mystery intensifies as Dupin confronts multiple dangers in his quest to save Camille from becoming another victim of Mirakle's monstrous experiments. Balancing logic and sheer bravery, Dupin delves into the darker underbelly of Parisian society, hoping to reveal the truth and put an end to the murders haunting the Rue Morgue.